Air conditioning system



Aug.1,1,1-942. H1 L SIEINFELD 2,292,496#

AIR coNDITIoNING SYSTEM 1 Filed Feb. 7. 1958 slsheets-slheet 1 im j Aug.l 11,1942. v` Hf L, sTElNFELD 4 42,292,486 In coNDITIoNlNG SYSTEM v A, FiiedvFeb. 7, 1933' s sheets-sheet- 5 Aug.v l1, 1942. H, L sTElNFELD 2,292,486'

l AIncoNDITomNfr-SYSTBM Filed Feb. "7, 19:58 sjsneets-speet 5 Sfnnc'nto; v Harold L..stem rew Bu l .I "w

Patented Aug. 11,1942

AIR CONDITIONING SYSTEM Harold L. Steinfeld, East Orange, N. J., assigner to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application February 7, 193s, serial No. 189,073

2s claims.

This invention relates to an air conditioning system and more particularly to a system of the type wherein the air within a space is heated, cooled, humidied or dehumidied according to requirements of said space.

One of the objects of my invention is the provision of an improved controlsystem for an air conditioning system of the above described type.

Another object of my invention is the provision of improved control means for a refrigeration system.

More specifically, it is an object of my invention to provide a refrigeration system wherein the temperature of the evaporator is controlled in accordance with the hum-idity of the space being conditioned, and the' effective area of the evaporator is controlled in accordance with the temperature -of the space being cooled, with im-- proved -control meansfor controlling the temperature and effective area of the evaporator.-

Another object is the provision of a novel control means for controlling the operation of a thermostatic expansion Valve used in a refrigeration system.

.Another object is the provision of a novel control means for controlling the operation of the compressor of a refrigeration system.

Other objects will become apparent' upon a study of the specification, claims and appended drawings Whereinlike reference characters represent like parts in the various views, and in which Figure 1 is a schematic view of one form of an air conditioning system embodying my invention;

Figure 2 isa cross sectional view of the thermostatic expansion valve illustrated inFigure 17 Figure 3 is a schematic view of a modication of the system illustrated in Figure l;

Figure 4`is`a cross sectional View of the differential pressure controller illustrated in Figure 3;

Figure 5 is a cross sectional view of the back pressure controller illustrated in' Figure 3;

Figure 6 is a schematic view of another form of air conditioning system embodying my invention: and

Figure f7 is. a schematic View of the air con-- ditioning system embodying my invention utilizing pneumatic controls.

In accordance .with my invention, a year around air conditioning system is illustrated wherein provision is made for heating, cooling, humidifying and dehumidifying according to the pipe 23 leading fromA the high pressure side of' requirements of the space being conditioned.

Heat and 'humidity are supplied to the space when the temperature and the humidity in the space are below predetermined values. An evaporator of a refrigeration system is provided for cooling or dehumidifying the air to the space being conditioned when the requirements of the space are such as to require cooling or dehumidifying. vThe same' temperature controller that controls the operation of the heating means controls the superheat at the evaporator outlet to vary the same in accordance with the temperature of the space so that the eiective cooling area of the coil is varied according to the amount of cooling required and the temperature of the cooling coil is controlled byf-the same controller that controls the operation of the humidifying means.

'I'he temperature controller also controls the temperature of the coil if the temperature in the space attains an excessively high value and the humidity controllerlcontrols the eiective cooling area of the coil if the humidity in the space attains a predetermined value. In other words,

the temperature controller normally controls the the temperature in thespace attains an excessive value.

Referring more particularly to Figure 1, an airconditioning chamber is represented generally by the reference character I0, this chlamber being provided withea fresh air inlet Il and a return air inlet I2, the inlets I I and I2 being.

controlled by dampers I3 and I 4 which may be manually or automatically controlled in any suitable manner. A' fan`I5 driven by a motor, I6 `draws air through the chamber IU and discharges itthrough'an outlet I1 into the space being conditioned. Mounted Within the chamber I0 is.

a -spray`l8 for supplying humidity to the space being conditioned, a heating coil I9, and an evaporator coil 20 of a refrigeration system.

'I'his refrigeration system may include a compressor 2| driven by means of a motor 22, a

the compressor to a condenser 24. A pipe 25 connects the outlet of the condenser to an expansion valve 26 through which the condensed refrigerantis expanded and then ows into the evaporator 28 wherein the expanded refrigerant picks up heat from the air surrounding the coil and becomes evaporated and then iiows through a pipe 21 back to the inlet of the compressor.

The details of the expansion valve are illustrated in Figure 2 and this valve may include a casing made up of sections 38, 3|, and 32. The section 38 includes an inlet 33 and an outlet 34, communication between the inlet and outlet being controlled by a valve comprising a valve member 35 and a. valve seat 36. The operating means for the valve member 35 includes a diaphragm 31 which may be clamped between the casing sections 38 and 32 as indicated in the drawing, diaphragm 31 being provided with a plunger 38 which extends into the casing section 38 through a packed joint 39. A capillary tube 48 connects the space beneath the diaphragm 31 with a bulb 4| illustrated in Figure 1, this bulb and tube being lled with a volatile fluid and the. bulb being mounted in intimate contact with the evaporator outlet so that the pressure beneath the diaphragm corresponds to the temperature of the refrigerant leaving the evaporator. The space above the diaphragm 31 is connected by means of a small pipe 42 to the evaporator outlet so that pressure in the space above the diaphragm corresponds to the pressure of the refrigerant leaving the evaporator. The

. valve is normallybiased toward closed position by means of a spring 45 acting between a plate 46 and a plunger 41 which bears against the top of valve element 35. A sealing bellows 48 is connected to'the plate 46 and to an annular plate 49 which may be clamped between the casing sections 38 and 3| or may be otherwise suitably connected tothe casing section 38 to prevent the leakage of refrigerant from the casing section 38. Provision is made for adjusting the position of the plate 46 and this includes a push rod 58 bearing against the top of the plate 46 and being seated within a recess therein, the upper end of this rod being pivotally connected at 6| to one end of a lever 52 in turn pivoted at 53 to an adjustable fulcrum 54. The opposite end of lever 52 is connected at 55 to an arm 56 operatively connected to a motor whereby the position of the plate 46 may be suitably adjusted in response to the conditions existing in the space as will be hereinafter set forth. Y

The position of the valve element 35 depends upon the force exerted by the spring 45, the pressure existing at the evaporator outlet and the temperature existing at the evaporator outlet and it is therefore apparent that the valve responds to the superheat at the evaporator outlet, the amount of super-heat required. to open the valve1 being dependent upon the force exerted by the spring 45, or in other words, upon the adjustment of lever 62. However, if plate 46 is moved downwardly suiliciently, it will engage plunger 41 and positively hold the valve closed, irrespective of the superheat existing at the evaporator outlet.

The operation of the compressor 2| is con.

trolled by a relay generally designated by the reference character 68, this relay comprising coils 6| and 62, an armature 63, switch arms 64 and 65 operated by the armature 63 and contacts 66 and 61 cooperating with the switch arms 64 and 65. Upon energization of the relay coil Y 62 the arms 64 and 65 are moved by the armature 63 into `engagement with'the contacts 66 and 61 and the compressor 2| is placed into 7 operation. Upon deenergization of coil 62, which is caused, as will be later described, by the energization of coil 6|, arms`64 and 65 are moved out of engagement with contacts 66 and 61 into the positions illustrated.

The outlet of the compressor is connected by a tube 18 to a bellows 1| which operates an arm 12 pivoted at 13 and held against the top of a bellows by means of spring 14. A mercury switch V15 is carried by the lever 12 and when the pressure at the compressor outlet reaches an excessive value the pressure Within the bellows 1| causes expansion of this bellows to tilt lever 12 and switch 15 to a. circuit opening position as will be readily apparent. Lines 11 and 18 connected to a suitable source of power (not shown) are provided for supplying power to the compressor motor 22. It will now be apparent that upon energization of relay coil 62, the compressor motor 22 will be energized by means of the following circuit: from the line 11 through conductor 88, arm 64, contact 66, conductor 8| through the motor 22, conductor 82, mercury ,switch 15 and conductor83 w the line 18. The compressor will. continue to run until coil 62 becomes deenergized or the circuit through the switch 15 is broken by reason/ of an excessive pressure on the high pressure side of the compressor.

Communicating with the suction side of the compressor by means of a tube 85 is a bellows 86 which operates a lever 81 pivoted at 88 and biased against the top of the bellows by means of a. spring 89'. Lever 81 includes arms L89 and 98 which are arranged to sweep over resistance 9| and center tapped resistance 92 in response to variations in suction pressure at the compressor. As the suction pressure drops, arm 89 moves to the leftand arm 98 moves upwardly, and as lthe suction pressure rises, the arms move in the reverse-directions.

The energization of relay coils 6| and 62 is controlled by means of a relay 85 which includes opposed balanced coils 96 and 91, an armature 98 connected to an arm 99 cooperating with contacts |88 and 8|. Energization of coil 91 to a greater extent than coil 96 causes movement of armature 98 to the right whereupon arm 99 moves into engagement with contact |8|. When the coils are equally energized, the armature 98 and arm'99 move to a mid-position, and upon energization of coil 96 to a greater extent than coil 91, the armature moves to the left, moving arm 99 into engagement with contact |88. Power may be supplied to the relays 68 and 95 by means of a transformer |04 including a primary |05 connected to the lines 11 and 18, and a low tension secondary |86. When the relay coil 91 becomes more highly energized than the relay coil 96 to move the switch arm 89 into engagement with the contact |8|, the lcoil 62 of relay 68 becomes energized through the following circuit: from one sideofthe transformer secondary |86 through conductors |88, |89, H8,

- contact |8|, arm 99, conductors H2, coil 62 and conductors ||3, ||4, and ||5 to the other side of secondary |86. `As previously stated the energization of relay coil 62 causes engagement of the switch arms 64 and 65 with their respective contacts, the engagement of arm 64 with contact 66 causing loperation 'of the compressor" motor 22. 'Ihe engagement of arm 65 with contact 61 closes a holding or maintaining circuit' for the relay coil 62, which circuit is independent of the engagement of 5 arm l sa with the contact lol, this circuit 65, conductor H2, relay coil 62, conductors H3, v

||4, ||5 to the other side of the secondary |06. The relay coil-:62 will therefore remain energized until the arm 99 of relay 9'5 is moved into engagement with contact which'will take place whenthe relay coil 96 of relay 95 becomes more highly energized than coil 91. When this happens, the relay coil 6| of relay 60 becomes en'- vergir'zed through the following circuit: -from the transformer secondary |06 through conductors |08, H6, contact 61, arm 65, conductor 4H arm 99, contact |00, conductor H8, relay coil 6| and conductors H9, H4, and H5 to the other side of the secondary. Coil 6| opposes the effect of the relay coil 62 so that the armature 63 is not attracted by the relay coils and the arms 64 and `|55 move out of engagement withthe `contacts 66 and 61 whereupon the maintaining circuit for the coil 62 is interrupted and the circuit kthrough the coil 6| is likewise interrupted since this circuit includes the maintaining arm 65 and contact 61. Y

It will accordingly be seen that the operation of the compressor is controlled by the relay 95. This relay is controlled by the potentiometer comprisingr resistance 9| and arm 89, which is in turn operated by the pressure at the suction side of the compressor, as follows: the resistance 9| is connected to the extremities of the relay coils 96 and 91, the left end of resistance 9| being,r connected by the conductors |22, |23, and |24 to the end of coil 91 and the right end of resistance 9| being connected by conductors |25 and |26 to the end of coil 96. The arm 89 is connected to the junction of the coils 98 and 91 by means of conductors |28, |29, the center tapped resistance 92 and the slider 90. It will therefore be seen that the resistance 9|'and the arm 89 are connected in parallel with the coils 96 and 91 pend upon the position of arm.89 withrespect to the resistance 9| and will therefore depend upon the pressure existing at the suction side of the compressor. Movement of the arm 89 to the left of the resistance 9| increases the ow of current through the coil 95 whereas movement of the arm 89 to the right increases the flow of current through the coil 91. It will therefore be apparent that as the suction pressure `decreases and the arm 89 moves to the left, that the coil 96 will become more highly energized than the coil 91, causing movement of armature 98- and arm 99 to the position which causes the energization of relay coil 6| and deenergization of relay coil 62 stopping the operation of the compressor. With the compressor at rest the pressure on thesuction side of the .compressor will'gradually increase until the arm 89 has moved sufficiently far to the right over resistance 9| to cause -the coil 91 to be more highly energized than coil 9S which in turn causes the energization of-relay coil 62 of relay 60 andtherefore the operation of the compressor. It will therefore be seen that the operation of the compressor is controlled by the suction pressure to maintain the suction pressure within desired limits.

Mounted Within thespace being' conditioned is a temperature responsive device. consisting of a jsbellews, |35 containing a volatile uid and acting against an arm |36 connected to a shaft |31 carrying contact arms |38, |39, and |40 suitably insulated therefrom. Arm |36 is held against the'bellows |35 by vmeans of a spring |4|. Arms |38, |39, and |40 are varranged to travel over resistances |42, |43, and |44, respectively, these resistances being so arranged that they are engaged sequentially by the respective arms. In other words, upon a progressive increase in. temperature arm |38 moves across resistance |42 and after it reaches the end of said resistance .l the arm |39 starts moving across resistance |43 and subsequently the arm |40 starts to move across resistance |44l after the arm |39 has left resistance |43. Upon a decreasein temperature the'reverse operation takes place.

Also mounted in the space to be conditioned is ahumidity responsive device |50 which may be of any suitable construction but is illustrated as comprising a plurality of hygroscopic ele- 'ments such as hairs xed at their upper ends to a support |52 and connected at their lower ends to an arm |53 fixedly mounted on a shaft |54. Arm |53 is biased downwardly by.means of a spring |55 and tends to cause the elongation of the hygroscopic `elements |5| as the humidity within the space increases. Shaft |54 carries arms |51, |58, and |59 arranged to sweep across rand that the energization of t ese coils will deresistances |60, |6I, and |62 which are arranged with respect to the arms in the same way as the resistances in the temperatureA responsive control device. In response to a rise in temperature ,the arms of the temperature responsive device move clockwise and likewise in, response to an increase in humidity, the arms of the humidity .responsive device move clockwise, the arms moving in the reverse direction in response to a decrease in temperature or humidity in the space being conditioned.

IThe arm |38 of the temperature controller controls the operation of the heating coil I9. .The

ow of a heating medium such as steam'through this coil is controlled by a valve |10 which valve may include' a valve4 stem |1| to which is connected a rack |12 operated by a pinion |13 of a motor |14. to the motor from a suitable power source. This motor is of the proportioning type and may be of the'form shown in the patent to D. G. Taylor 2,028,110 issued January 14, 1936. Such a motor includes opposed relay coils such as the relay coils 96 and 91, the energization of one coil causing rotation of the motor in one direction and the energization of the other coil causing rotation of the motor in the opposite direction. Resistance .|42 is connected by means of conductors and 8| to the extremities of these coils and the arm |38 is connected by means of a conductor |82 to the junction of the relay coils, the extremities of the vcoils also being connected to the leads |15 and |16. It `will therefore be apparent that the movement of arm |38 over the resistance |42 will control the energization of the relay coils and cause the motor to rotate in one direction or the other. As illustrated in the Taylor patent aforementioned the motor also includes a balancing potentiometer which is operated when the motor rotates, this balancing potentiometer being connected to the relay coils in parallel with the potentiometer 42 and op. erated in a direction to oiset the eiectof potentiometer |42 so that the motor will rotate in one direction or the other an amount corresponding to the movement of arm 38 over the,

tentiometer and the motorlwill come to rest.

The valve |10 is thus voperated by the temperature controller to open or close the vlave in ac- Leads |15 and |16 supply power .cordance ,with temperaturevin the space, or in other words, in accordance with the position of arm |38 with respect to the resistance |42.

' When the temperature in the space reaches such a value that the arm |38 is at the upper extremity of resistance |42 the valve will be fully closed and no. heat will be supplied to the coil I9. When the arm |38 is at the lower extremity of resistance |42 the valve will be in wide open position and the coil |9 will be operated at max-l coils of said motor, the junction of. these coils being connected by means of the conductori |92 to the arm |51. This motor will operate the valve to supply a maximum amount of moisture to the air when the humidity is at a minimum value and the arm |51 is at the lower extremity of resistance |60. When the humidity attains a high enough value so thatv arm |51 is at the upper end of resistance |60-the-motor is rotated to a position wherein the valve |85 is fully closed and no moisture is being supplied by the spray I8 to the air being conditioned.

The relay 95 controlling the operation' of the compressor which relay is controlled by the controller 89, as previously set forth, is also controlled by the arm |58 of the humidity controller so thatwhen the humidity in the space reaches a high enough value so that the arm |58 starts to move across resistance |6|, this arm and resisty ance exert a controlling function over the relay 95. The arm |58 is connected to the junction of the coils 96 and 91 of the relay 95 by means of the conductor |28, conductor 200, a rresistanceelement 20|, a conductor 202, the arm |40 of the temperature controller and the conductor 203. The end of relay coil 91 is connected by means of lconductors |24, |23, 205, and 206 to the left'end of the resistance |6| and the relay coil 96 is,con nected by means offconductors |26, 201, and208 to the right end of the resistance I6 It is therefore seen that Athe potentiometer 6| is connected to the, relay coils in parallel with the potentiometer 9|, the arm of the potentiometer |6| bemg connected to the junction of the coils through the arm |40 of the potentiometer |44. By reason of the provision of the resistance 20| in the circuit to the arm |58 of potentiometer |6| the effect of this potentiometer is less than the eect of potentiometer 9| on the relay 95. In other words, movement of arm |58 from the left end to the right end of resistance |6| will be balanced by the movement of ann 89 over resistance 9| through a relatively short distance. With the arm 58 in the position illustrated it will be noted that the coil 96 of the relay 95 is energized more highly than the coil 91 as far as this potentiture 98 moves to the right starting the compressor as heretofore explained. The operation of the compressor forces refrigerant through the expansion valve 26 and the evaporator 20, this flow being controlled by the valve 26 and the compressor will continue to'operate until the arm 89 has moved to the left of resistance 9| a sufficient amount to cause coil 96 of relay 95 to be more highly energized than coil 91 whereupon the compressor will come to rest. As stated before it takes a relatively small movement of the arm 89 of resistance 9| to counter-act the eiect of a large movement of arm |58 over the resistance |6| and the control range of the arm 89 on the resistance 9| depends upon the position of arm |58 with respect to the resistance |6|. As the arm |58 moves farther to the right over resistance, |6| indicating a higher humidity in the space being conditioned the control range of the potentiometer 9| is shifted to the left so that lower suction pressures will be maintained by the compressor and therefore'a lower coil temperature at the evaporator 20 will be maintained thus increasing the dehumldilying effect of the coil 20 of resistance |44. Should the temperature in the ometer is concerned since the only resistance in the circuit through the coil 96 is the resistance 20|. f As the humidity within thespace starts to increase and the arm |58 starts to move over the res1stance |6|- the resistance in series with the since this effect is dependent primarily upon the coil temperature. The provsionof resistance 92 in series with the arm 89 and the`- junction of the relay cfoils 96 and 91 insures that the control range of the potentiometer 9| will always be the same length regardless of whether the control range is at the center of the resistance' or at either end thereof.

It will be noted that the right end of resistance |44 is connected to the right end of resistance- |6| by means of conductor 208 and these ends of resistances are connected by means of conductors 201 and |28 to the left end of the relay coil 88. The arm |40 which cooperates with resistance |44 is connected by means of the wire 202, resistance 20|, and conductor 200 to the junction of the rela-y coils 96 and 91. Since the controller |40 is intended to act only as a limit controller and to have no control function whatever over the relay 95 unless the temperature reaches such a high value that arm |40 moves over the resistance |44, a resistance 2|0 is connected between the conductor 203 which connects to the left of resistance 44 and to the conductor 205 which vconnects to the extremity of coil 91. This reeffect whatever upon the relay 95 when the arm 40 is positioned as shown at the extreme left end space reach such a high value that the arm |40 starts moving across resistance |44, this controller will increase the energization of coil 91 and decrease theenergization of coill 96 and move the control range of the controller 89 further to the left whereupon a lower suction pressure will be `maintained by the compressor and a lower coil temperature will be maintained at the evaporator 20. The controller |40 will therefore control theY compressor to maintain lower suction pressures whenever the temperature in the space reaches a l suiliciently high value even if the humidity is so low that the arm |58 is at the left of resistance' |6|, the controller |40 'acting as a limit control.

It will therefore be seen that the temperature maintained at the evaporator 20 is 'controlled primarily by the humidity responsive device, the temperature responsive device under normal conditions having no effect on the temperature being maintained by the coil but under extremely high temperature conditions this temperature responvalue equal "to that of the resistance |62 is connected between the conductors 2|`| and 229, resistance |62 being connected between the conducsive device will exert its effect on the coil teinperature to lower the same.

Referring now to the expansion valve 26, the tension of the spring 45 is controlled by the motor 2 |5 to which the arm 2|6 is connected and by means of the link 56 connected to the lever 52 whereby the tension of the spring is varied in accordance with the position of arm 2|6. `Rotation of arm 2 |6 in a clockwise direction causes the rod 50 to be moved upwardly and thus the force ex'.

erted by the spring 45 on the valve 35 is decreased so that a lesser degree of superheat at'the evaporator outlet is required to open the valve. As the superheat maintained atthe evaporator outlet decreases, .the'effective cooling area of the coil 20 increases. Accordingly, the effective cooling area is increased as the arm 2|6 of motor 2|5 moves in a clockwise direction and the effective cooling area'is decreased as this arm moves in a counter-clockwise direction. Should the arm move far enough in this direction, plate 46 will engage plunger 41 and positively hold the valve closed.

'I'he motor 2 |5 may be ofthe same type as motor |14 and includes opposed relay coils similar t0 the coils 96 and 91. The junction of these coils is connected by means of a. conductor 2| 1, the

. evaporator.

arm |59 of the humidity controller, conductor 2 I8 v to the arm |39.of the temperature responsive device. The end of one of the coils is connectedby means of a conductor 220 to the left end of resistance |43 and the end of the other relay coil is connected by means of a conductor 22| and conductor 222 to the right end of resistance |43. When the humidity is not excessively high so that arm |59 has not started to move over resistance |62, the motor 2|`5 will be controlled directly by the controller |39 and the degree of rotation of arm 2 I6 will 'be in direct proportion to the extent of movement of arm |39 over resistance |43.

Thus as the temperature in the space starts to rise and the arm |39 moves to a certain point on resistance |43, the motor 2|5 will operate until the eilect of the potentiometer |43 is counter-balanced by the effect of the balancingpotentiometer within the motor 2|5, the arm 2|6 coming to rest ina new position; having moved clockwise from'that illustrated, thus decreasing the tension of spring 45 within theexpansion valve 26 and thus increasing the effective cooling surface of the coil 20. In other Words the tension of the spring 45 of the expansion valve is adjusted in direct accordance with the position of the arm |39 ofthe temperature responsive controller. It is therefore seen that the main control over the effective cooling area of the evaporator is by the temperature responsive device to increase the effective cooling area as the temperature increases and vice versa.

The resistance |62 of the humidity responsive device acts as a limit control and vcauses the operation of motor 2|5 in a direction to move' arm 2 6 clockwise if the humidity in the space reaches van excessively high value so that arm |59 moves over resistance |62 regardless 0f the temperature being maintained within the space. Resistance |62 is connected to the resistance |43'and the motor 2|5 in the same manner as resistance |44 is connected to the relay 95. Conductors 222 and 223 connect the right portions of the resistances |43 and |62, the arm |59 of the controller |62 being connected directly to the junction of the relay coils as aforedescribed. In order that the resistance |62 will have no effect on the motor when the arm |59 is at the left end of the re sistance, a resistance 235 having a resistance tors 2H and 22| when the arm |59 is off the resistance |62.

v Under normal conditions therefore the control of the effective cooling area of evaporator 20 is bymeans of the temperature responsive device,

the humidity responsive device having no eect whatever unless ,the humidity inA the space reaches an excessive value whereupon the arm |59 is caused to move over the resistance |62 vand ,cause the operation of motor 2|5 to relieve the tension of the spring within the expansion valve and increase the elective cooling area of the In the system of Figure 1, whenever the humidity within the space is below a desired value the valve- |85 will be controlled by the humidity re sponsive device |50 to supply moisture to the space being conditioned. When the humidity rises to a high enough value, valve |85 will be moved to closed position and prevent the supply' of moisture to the air. If the humidity should rise above a desired value, whereupon the arm |58 starts to move across the resistance IGI, -the suction pressure maintained by.\the compressor will be lowered and the compressor will operate to f maintain the temperature at the evaporator 20 progressively lower as the humidityin the space increases. The heating coil |9 is operated by the temperature controller to supply heat` I to the space in accordance with the temperature therein, the valve I'l being closed when the temperature reaches a desired value, preventing the supply of heating medium to the coil I9. If the of the evaporator 2U. Should the humidity in' crease to an excessive amount while the temper- `ature in the spacev is at or below the desired value,

the humidity controller will, in addition to con: trolling the temperature of the evaporator 29, also control the elective cooling area thereof. 0n the other hand if the humidity is at or below the desired value and the temperature should reach an excessively high value the temperature controller will lower the temperature of the evaporator .as well as increasing the effective cooling area thereof. Thus by means of a single humidity responsive device and a single temperature responsive device the temperature and humidity of a space being conditioned is very effectively controlled during both the heating and cooling seasons.

Referring now to Figure 3, an air conditioning chamber having heating, humidifying, and cooling coils arranged in the -same manner as in Figure 1 is illustrated. The heating coil I9 and humidifying spray |8 may be controlled in exactly the same manner as in Figure' 1 and further description thereof is unnecessary. Likewise the ellective cooling area of the evaporator 26 is controlled primarily by the temperature in thespace but may also be increased il the humidity 'in the space reaches an excessive value, the means for controlling this effective area being identical to that of Figure 1. The means for controlling the temperature of the coil are however different from that shown in Figure 1.

The operation of the compressor is controlled in this gure by adifferential pressure controller indicated generally by the rference character 250 and illustrated in detail in Figure 4. This controller comprises a pair of bellows an'd 252 closed at their upper ends and connected by means of pipes 253 and 254, respectively, to the high' and low pressure sides of a back pressure valve 255. A lever 256 pivoted by means of a knife edge pivot 251 has its ends in engagement with plungers 258 and 259 connected to the upper 265 of an arm 266 pivoted at 261, the arm 266 carrying a mercury switch 268. As the pressure differential within the bellows 25| and 252 increases the lever 256 is caused to move about the pivot 251 vin a clockwise direction moving the pin 264 to the right and causing movement of arm 266 about the pivot 261 in a direction to tilt the mercury switch 268 to the left. Mercury switch 268 includes contacts 210 and 21| and a mercury element 212 and it will be readily apparent that as the pressure diierential between the bellows reaches a high enough value the mercury switch will be tilted to a position wherein a circuit through contacts 210 and 21| by the -mercury element 212 will be interrupted.

Mounted in the path of downward movement of the right end of lever 256 is a pivoted arm 215 held by means of a spring 216 against a stop 211. The upper end of spring 216 is connected to an adjusting screw 218 whereby the tension of the connected to the lower end of a rod 30| pi'vot spring may be readily adjusted. The force exerted by the spring 216 is added to the force exerted by the spring 260 and as the pressuredifferential between the bellows 25| and 252 starts to increase the right end of arm 256' will move downward rather rapidly until it engages the arm 215. In order for the switch 268 to tilt farenough to break the circuit through contacts 210 and 21| the arm 256 has to move downwardly farl enough to move the arm 215 away from the stop 211. 'I'his movement is resisted by the spring 216 and the lever 256 will remain in engagement with the arm 215 until the pressure differentialhas increased a considerable amount sufficient to stretch the spring 216 whereupon, the switch 260 will tilt far enough to breakthe circuit between contacts 210 and 21|. As the pressure differential starts to decrease the spring 216 will quickly move the arm 215 against the stop 211 carrying the lever'256 therewith. The circuit through the contacts 210 and 21| is still interrupted at this time and will remain intermpted until the presthe circuit through contacts 210 and 21| will not be remade by the mercury 212 until the pressure differential has dropped suiliciently for the spring 260 to move the arm 256 upwardly. Whereas the inherent differential of the mercury switch is relatively small, the use of the spring 216 permits ,a wide'dierential in the operating range of this pressor motor 22, conductor 282, thev mercury switch 15 of the high pressure cutout and the conductor 283 to the line 11. It is accordingly seen that the compressor will be operated whenever thepressure diierential across the valve 2 .55 drops to a predetermined low value and stops whenever the pressure diilerential increases to a predetermined high value.

The back pressure valve 255 isillustrated in detail in Figure 5, and this valve includes an inlet 290, a valve member 29| cooperating with a valve seat 292 and an outlet 293. The valve is provided with a valve stem 295 extending vertically'upwardly therefrom, the valve stem 295 being suitably connected to a diaphragm 296.

Diaphragm 296 may be clamped between sections 291 and 298 of the valve body and a spring 299 biases the diaphragm 296, downwardly and the valve 29| to closed position. 'I'he upper end of the spring is received in a spring retainer 300 ally connected to the end of a lever 302 having an adjustable fulcrum 303. The opposite end ol the lever 302 is pivotally connected to a link 306 by which the lever 302 is connected to the arm 305 of a motor 306, whereby the position of the lever 302 and the force exerted by spring 299 may be varied. A second spring 308 bears against the underside of the valve 29|, the opposite end of this spring bearing against a plate 309 supported-by an adjusting screw 3|0 having a suitable operating handle 3| Sealing bellows 3|2 is connected to the plate 309 and to an annular plate 3|3 held between the main valve body and the section 3H whereby the discharge side of the valve is eiectively sealed from the atmosphere. The spring 308 is provided to vary the effect of the spring 299 on the valve for any given position of the spring retainer 300.

The operation of this valve will be readily apparent. As the pressure of the refrigerant entering the inlet 290 reaches -a value sufficiently high to overcome the effector spring 299, the pressure will exert an upward force on the diaphragm 296 whereupon the valve will be lifted rom its seat, thus permitting the passage ofrefrigerant therethrough 'to' the compressor. By adjusting the force exerted by the spring 299 the-back pressure necessary toopen the valve may be readily adjusted.

The temperature of the refrigerant flowingthrough the evaporator 20 will vary in accordance with the back pressure. As 'the back pressure is decreased the refrigerant will pass through the evaporator at a lower pressure and a lower coil temperature will be maintained whereas upon an increase in the back pressure the coil temperature Iwill be increased. Therefore by varying the force exerted by the spring a conductor 320, the arm |40 of the temperature controller, conductor 32| to the arm |58 of the humidity controller. 'I'he end of one of the relay coils is connected by means of conductor 322 to thev left end of resistance |6| and the other end of this resistance is connected by the conductor 324 to the extremity of the other relay coil so that the motor is operated in accordance with the'position of arm |58 on the resistance |6| and the spring 299 of the back pressure valve is adjusted to exert less force on the valve as the humidity in the space being conditioned increases whereby the temperature of the refrigerant flowing through the evaporator will decrease in accordance with the increasing humidity in the space. Resistance |44 of the temperature controller is connected to the motor 306 in the same manner as in Figure 1 to act as a limit control, the right end of this resistance being connected by means of conductor 326 to the right end of `resistance |6| and the resistance 2 I0 being connected between the conductors 322 and 320 to offset the eiect of resistance |44 which is connected when the arm is at the left of resistance between the conductors 320 and 324 so that the resistance |44 has no effect on the motor 306 o'r the temperature of the refrigerant owing through the evaporator unless the temperature in the space attains an excessively high value. Should the temperature in the space reach a high enough value so that the arm 40 vmoves over the resistance |44, the motor 306 will operate to decrease the elect of spring 299'regardless of the humidity in the space, to thereby lower the temperature of the coil 20.

The use of the back pressure controller forms a very effective method of controlling the temperature of the evaporator according to the demand upon the evaporator since the cooling effect of the evaporator will vary in accordance with the pressure lof the refrigerant therein.

By using the differential pressure controller foroperating the compressor, the back pressure on the compressor will be maintained at a maximum value since the compressor operates only when -the differential across the backpressure controller is at a minimum value, so that the compressor operates at maximum eiciencyfor any pressure maintained within the evaporator.

In other words, the back pressure on the compressorwi1l vary in accordance with the pressure maintained in the evaporator.

The cycle of operation of the system in this iigure is precisely the same as that of Figure l,b

the only dilerence being in the ,means for controlling the operation of the compressor and the means for controlling the temperature of the evaporator coil.

In the system illustrated in Figure 6, the saine cycle and method of operation as that illustrated in Figure 3 is employed in connection with a unit air conditioner utilizing self contained temperature responsive elements on the various controlled devices.

An air conditioning chamber is represented by the reference character 400, this chamber ininlet 402. Mounted within the chamber 400 are the spray pipe I8, the heating coil I9, and the cooling or evaporator coil 20. A fan 403ls provided for drawing air through the chamber- 400 and supplying the conditioned air to the space which is to be conditioned.

A valve 405 is positioned in the steam line to the coil I9 for controlling the supply of steam to this coil. This valve may bea conventional diaphragm valve having aiidiaphragmffin.they chamber 406 by which the position of the valvM ls controlled. `A capillary tube 401 connects the diaphragm chamber 406 to a bulb 408-positined in the path of return air to the conditioner, the tube, bulb and space above the diaphragm in the chamber 406 being lled with a suitable volatile fluid which expands upon a rise in temperature in the return air duct. The valve is accordingly positioned in accordance with thereturn air temperature.

The spray I8 is controlled by a valve |85, a`

motor |89, anda humidity responsive device in the same manner as illustrated in Figures 1 and 3 whereby the air is supplied with moisture when the humidity within the space being conditioned is below. a predetermined value.

The valve 26 for controllingthe ow of refrigerant from the condenser 24 to the evaporator 201s providedwith a bracket 4|0 on which is positioned a motor 4| and a bellows 4|2. Pivotally supported at 4|3 to the end of the bracket 4|0 is a lever 4|4having a portion 4|5 resting on the top of the stem which controls the This lever is urged against the top of stem 50 by means of a spring 420 connected at its lower c end to the bracket? and adjustably connected at v its upper end by means of anA adjusting screw cluding a fresh air inlet 40| and a return air 75 42| to the lever 4|4. The bellows 4|? is positioned to the left of the pivot 4|3 and is connected by means of a capillary tube 422 to a bulb 423 located in the return air line to the chamber 400, this bellows having a plunger 424 extending upwardly from the top thereof and engaging theunderside of the lever 4|4. The bellows 4|2, tube 422, and bulb 423-are lled with a suitablevolatile iiuid andas the temperature within the return air line increases, the uid within the bulb, tube, and bellows expands causing the expansion of the bellows 4|2 whereupon the lever 4|4 is urged upwardly against the bias of spring 420. It will readily be lseen therefore that upon a rise in return air temperature to asuciently high value, the tension of thespring 45 within the ex'pansion valve is reduced by reason of the upwardvmovement of lever 4|4 whereupon the effective cooling area of the evaporator coil 20 is increased in accordance with an increase of return .air temperature.

Operated by the motor 4| is a push rod 430 which acts upon a lever 43| pivoted at 432I and having an end-` portion extending under a projection of the lever 4|5. Operation of the motor 4|| causes. the plunger 430 to be moved up orv down whereupon the position of the lever 4|4 may be raised by the lever 43| upon a suflicient movement of the plunger 430 upwardly. This motor is controlled by the humidity responsive element and more particularly by the arm |40 and resistance |44. This motor may be offthe arm -|40 and the opposite ends of the coils are connected by means of conductors 435 and 431 to the ends of resistance |44. It will be' readily understood that when the humidity in the space reaches an excessively high value, or in other words, when the arm |40 moves over the resistance |44 in response to an excessive humidity in the space being conditioned the motor 4|| will be caused to move the plunger 430 upwardly un amount proportional to the amount of movement of the arm |40 over the resistance |44. If this movement of the plunger 430 by the motor 4|| is suiiicient to raise the lever 43| beyond the position of the projecting portion of lever` 4|4, this lever will be moved upwardly farther than it is moved by the bellows 4|2 and the valve 25 will be caused to open in response to a lower superheat at the evaporator outlet so that the eiective cooling area of the evaporator coil is thereby increased. A

By this arrangement the expansion valve is operated `primarily by the temperature of the return air to the air conditioning chamber but should the humidity in the space reach an excessive value the humidity responsive device may assume control over the valve to decrease the tension of the spring and increase the effective cooling area of the evaporator coil, the cycle of operation here being the same as in Figures 1 and 3. The compressor 2| may be operated in the same manner as in Figure 3, the control means thereforincluding the differential pressure control 250'of the same construction as that shown in Figure 4 and the high pressure cutout similar to that of Figures 1 and 3.

The back pressure controller 2,55 may be identical in i'nternal construction with that of Figspring 443 is connected to the bracket 440 and' to the lever 44| by means of an adjusting screw 445. Positioned to the left of the pivot of lthe lever 44| is a' bellows 445 having a portion 441 acting against the lever 44|. A capillary tube 445 is connected to the bellows 445, this tubel being connected at its other end to a bulb 443,-the bellows, tube, and bulb being lled with a suitable volatile iluid. A motor 450 is supported on the Opposite end of the bracket 440,v this motor being similar in construction to motor 4|| and including a plunger 45| and a lever 452 pivoted at 453. Lever 452 extends under a projecting portion of the lever 44| as illustrated in the drawings. The motor 450 is operated by the arm |35 and resistance |43 of the humidity controller. .Wires 455. 451, and 455 connect the controller to the motor in a manner heretofore set forth in connection with motor 4| I.

The motor 450 and lever 452 form the main control for the back pressure valve 255 since the bellows 445 is set to respond only to an-excessive temperature of the return air and it is contemplated that under normal conditions this bellows will have no eect upon the position of the lever 44|. Accordingly as the humidity in the space rises to such a value that arm |35 moves across resistance |43, motor 450 will operate to raise the free en d of lever 452 which in tum will cause the free end of lever 44| to be raised, thus permitting the rod 30| to rise and lower the tension of the force exerted by spring 298 so that the back pressure required to open the valve will be decreased and the temperature of the refrigerant within the evaporator will be lowered so as to obtain an increased dehumidiiying effect of the coil 2,0.

If the temperature of the return air should reach an excessive value even though the humidity vis not high enough to operate' the back pressure. valve 255, the lever 442 will be raised by the bellows 445 thus allowing upward movement of rod 30| and decreasing the tension of the spring 299.

It will thusbe seen that in this form of the invention the sequence of operation is substantially the same as that of Figure 3 but the electric motors controlled by the temperature controller have been eliminated and replaced by the self-contained temperature responsive elements. While the bulbs 408, 423, and 449 have been shown as being positioned within the return air duct it is obvious that they could be located at any suitable place in the room being conditioned if desired. It is also obvious that the system illustrated in Figure 1 might be provided with self-contained temperature responsive operating units if desired.

Referring now to the form of invention shown in Figure 7 the same sequence of 'operation and the same results are obtained with the use of a pneumatic control system in place of the electrical control system shown in the preceding iigures.

An air conditioning chamber 500 is provided with a return'air inlet-50| and a fresh air inlet 502, a fan 503 and an outlet 504. The heating coil I3 and the evaporator coil 20 are positioned in the chamber 500 and a humidifying means 505 is also positioned in the chamber. This humidifying means is represented as being in the form of a tank 505 located in the bottom of the chamber 500 and being supplied with water by means of a pipe 501 controlled by means of afloat 505 to maintain a constant level of water in this tank. A heating coil 509 is positioned in the tank for heating the water therein, the supply of heating fluid through this coil being controlled by a valve 5|0.

AThe refrigeration system for supplying refrigerant to the evaporator 20 may be similar to that illustrated'and described in Figure 3, the compressor being controlledand operated in a similar fashion, namely, by the use of a differential controller and a high pressure cut-oil.

Mounted within the space being conditioned -is a thermostat generally indicated by the reference character 5I2, this\thermostat being of conventional construction and nay include a cylindrical element 5|3 having a high coeilicient of expension, this element carrying a rod 5I4 adiustably connected to the top of the element 5|: by

a screw threaded member 5|5. The lower portion of the member 5|3 is nxed, and mounted in the path of movement of the rod 5|4 as the cylinder 5|3 expands or contracts is a bell crank shaped ilapper valve 5|5 pivoted at 5|1. A nozzle 520 is positioned in the path of movementof a napper valve 5|5 and as the cylinder 5|3 expands in response to a temperature within the space the valve 5|5 will be permitted to pivot about 5|1 into a position in which the flow of air from the nonle 520 is cut oil. The adjusting member 5| 5 has connected thereto an arm 522 pivotally connected to an arm 524 operatively i the supply of heat to the 'coil 509.

Y,connected to a' bellows, 525 and it will apprentthat as the bellows` 525 expands or conp, o 9 the humidity suppi'irtcine air being conditioned l' is reduced to aminimum.

tracts the control point of the thermostat l2'l may be readily` adjusted. The operation of this bellows 525 will'b discussed below. i

Also mounted within the space being conditioned is a humidity responsive device indicated generally by the reference character 530. This device includes anyrconventional form of humidity responsive element 53| connected at its upper end to the adjustable screw member 532 yscrew threadedly received in the\upper portion 533 of a supporting member 534, the lower end of humidity responsive element 53| being connected to the pivoted dapper valve 535. A spring 536 connects to oneend o! this iiapper valve, the other end of this spring being connected at 531 to the supporting element 534. .Cooperating with the flapper valve 535 is the nozzle 535 of an air line and it will be readily apparent as' the huto procure humidicatioir'in the air conditioning chamber includes a valve element 550 cooperating with the valve seat 55| and a bellows 552 supported by a cap 553 and operatively connected by mea-ns of a valve ste'ni 554 to the valve element. A s'pring 555 is provided for biasing the valve towards open position and as the pressure within the bellows 552 increases, the valve is moved towards closed position, thus cutting off Air is suppliedto the bellows 552 by means of The valve 510 for controlling the supply of steam or other heatingmedium to` the heating coil |9 may be of the same. construction as the valve 5|0 and may include a valve element 51|,y valve seat 512, arr operating bellows-- 513; and

. spring 514. A branch line 515 connects the air supply line 560 with a restriction 511 having adjusting means 516, a pipe 518 leading from.v the outlet of the restriction'and connected to the interior of the bellows 513.l This pipe 518 also f connects a pipe 519-fleadlng to the nozzle 520. As the temperaturein the space being coni-i ditioned increases, the flap'per valve 5|6 mo`ve towardsclosed position, the supply of airissuing from nozzle 520 decreases and the pressure with,- in the bellows 513 increases whereby the valve moves Vtowards closed position; After the tem-x .perature has increased to a predetermined amount the supply of air leaving the nozzle 520 will have decreased sufficiently so that the pressure within the bellows 513 will have caused complete closureof the valvel 51| and .the supply of steam to the? coil 5|9` will beV entirely'off.

A reverse acting relay is represented. by the vreference character 580 and 'this relay.' may be of the same construction as that shown and d'escribed in theapplication of John Mzliarson and Karlligenbaun'r, Serial' No. 158,744 iiled August 12,-1937. Thisfrelay mayicomprise generally a body 58| -having' an air supplyV inlet 58,2, arr air outlet 583,- anda relief outlet 584. Thep'ort 584 is controlled by a valve element 585 connected to the' bottom* cross piece 586 of a yoke'581 which A surrounds the b'ody 58|. ,A s'pring 588i is prio vided for biasing the valve element 85toicl'o'sed. position and the yoke 581 downwardly. ,Com-1f.

, municating with the valve chamber 590 byrneans- Y opening in the ripper part of the body 58|.

an an une son having a binnen une ssi provided with a restriction 552 having a, suitable adjust-- ing means 553 for' controlling the flow of air therethrough. The outlet of' the restricting means 562 is cOnnectedto a. pipe 564 and to this pipe is connected the bellows 552 by means of a pipe 565. pipe 566 terminating the nozzle 538. It will, now be apparent thatiwhen the nozzle 538 isopen,

A the pressure within the bellows 552 will be' relieved since there is only a restricted ilow of air through the restriction 562' and the spring 555 will accordingly maintain the: valve 550- in open The pipe 564. isv also connected' to a position. As the humidity inr the space starts to increase and the humidity responsive element 53| becomes elongated, the dapper valve S535 is moved under the influence of spring 531 towards closed position whereupon the flow of air',` from the nozzle-538 is reduced and the pressure begins to build up within .the bellows 552 thus causing the valve to begin moving towards closed position and cutting down the supplyof steam to4 the coil 509. The' amount of air that is allowed to leak` through the nozzle'538 will be indirect' relation to the humidity within the space and accordingly thevalve 550 will .be moved to a position corresponding to the relative humidity 1 and after the humidity reaches a high enough value thus cutting down'the flow of air from the outlet 538 to asuflicient extent, the force exerted Mby;theibellows 532 will'be sufiicient to cause com.'

plete closure dfthe valve thus definitely cutting nfr the leimnlv of steam tothe coil 509 whereupon of a port 59| is a bellows 592 fixed to'l the 'rippen' walll of this valve chamber' and located in an? The upper portion of this bellows bears agairrstaI strap1593 and it?` will be readily apparent asifthe' pressure within the valve chamber increases the bellows 592 expand and thus: move the valve towards open position; Connected to the top" Wall of the body 58| by means oi a nipple 594 is a second bellows 595 the upper portion of which` is connected'to the top strap of the yoke 581iI This bellows connects by meansfy of a pipe 596?- to the pipe 566 which leads fronr the restriction'si o 562 to the nozzle 53B. Air is supplied to the' valve chamber 59|)v by means of" am air line 609)! leadingtoa, restriction 60| having adjusting I, means 602, a pipe B03 leading from. the restriction to the valve chamber. f Y The valve: 585 will be moved yto open position whenever the combined pressure existing in 'the bellows v592 and 595 is suicienttocovercom'e the force of spring 588. Assumingthat this spring exerts a force of 15 lbs.vto 'close'.'the-valva it'will `be apparent that the combinedV pressure in the bellows 592 and -595-must be '15"1bs. vbefore the valve will begin to open. AThe pressurev existing within the bellows 595 will depend upon the pressure in the. line5||i` which in turn dependsv upon the position of the'valve 5352 Assuming that this valve is wide open the humidity in the space being relatively lowj there willibefno vpre'sly sure within the bellows 595 so-rthat a-i-pressure of 15 lbs.,will haveto be built up r withinif the bellows 592 before the valve 2. 585 beginss to open. The pressurejn theloutlet 583 fromith'e valve 5 chamber will be the sanieas that-within the 1o bellows 592 so'that the pressure of the air pass- I ing through this pipe will be the same as that which is built up within the bellows 592 before the valve begins to open. As the humidity within the space begins to increase and the ow/ of lbs. as formerly. Accordingly as the pressure in the line 566 increases the pressure in the line 583 will decrease proportionately.

The line 583 connects by means of branch lines 6|U, 6| with accumulators 6|2 and 6|3. These accumulators may comprise suitable expansion elements iixed at their upper ends and biased to collapsed position by means of springs 6|4 and 6|5, respectively. Carried by the bottom of these 'expansible elements by means of'rods 6|6 and 6|`| are valve elements 6| 8 and 6|9, respectively. These valve elements control the ow of air from ports' 620 and 62|. The port 628 connects by means of a pipe 622 and 623 to a restriction 624 to which air is admitted by means of an air supply pipe 625. Pipe 622 also leads to the interior of a bellows 638 mounted on a bracket 63| suitably fastened to the top of the back pressure valve 255. As the pressure in bellows 630 decreases the bellows contracts and permits the lever 632 connected to the rod to move upwardly thus relieving the tension of spring 299 and lowering the backl pressure on the compressor.

The expansible element 6 l2 is designed to start opening when the pressure existing therein begins to drop from a maximum value which is maintained therein when the nozzle 538 is wide open vand the pressure in line 583 is at a maximum.

For example, assuming a line pressure of l5 lbs. when the pressure drops to 9 lbs., for example,l

this valve will begin to open and Aat 6 lbs. the

valve`may be wide open. The opening of this valve relieves the pressure in the line 622 and therefore the pressure within the bellows 630 thus reduces the back pressure on the compressor. It will be apparent therefore that as the humidity in the spaceincreases to a high enough value the pressure in the line 596 increases, the pressure in the lines 583, 6|ll, and 6H decreases permitting the valve 6|8 to openv whereupon the pressure within the bellows 630 decreases and the temperature of the evaporator -coil 29is lowered in response to the rising humidity.l

A second reverse acting relay 640 similar in n construction to the relay 580 has the upper bellows 64| connected by pipe 642 to the pipe 519 leading to the nozzle 520 of thermostat 5|2.- Air is supplied to the lower bellows 643 by means of an air supply line 644 provided with a restriction in the bellows 660 which will cause an expansion 645 from which line 646 leads to the valve chamber 641. This valve chamber communicates by means of a pipe 648 with the bellows 649 and 658 of a pair of accumulators similar to the accumulators 6| 2 and 6|3. The accumulator 650 is designed' to permit the opening of the valve 652 whenthe pressure in the bellows drops to 9 lbs., for example, assuming an air line pressure of -15 lbs. This valve'controls the exhaust of air from a pipe 653 connected to pipe 654 to which air is supplied from the supply line 655 through the restriction 656 and thepipe 651. Air is also delivered from the pipe 651 by means of a pipe 658 to the interior of a bellows 660,supported on a bracket 66| which in'turnis'suitably mounted on the upper portion of-the expansion valve casing 26. A drop in pressure in the bellows 668 permits the lever 66| which connects/the bellows and the valve stem 50 to/pivot in a counterclockwise direction and relieve the tension of the spring 45, it being understood that this valve has the same internal construction as that shown in Fig. 2.

It will now be apparent that when the temperature in the space reaches a sufficiently high value so that the pressure inthe bellows 64I builds up by reason of the movement of flapper valve 5| 6 towards the orifice 520, this building up in pressure being accompanied by a decrease in bellows 643 and therefore in-the accumulator 650, the spring biasing the bellows will cause the valve 652 to move away from 'the end of pipe 653 thereby allowing the venting of air from the bellows 660 which in turn decreases the tension of the spring in the expansion valve allowing theI ,valve to open in response to a lower superheatv whereby the 'effective cooling area of the evaporator coil 28 increases.

It should be understood lthat the initial rise in humidity causes a collapse ofthe bellows 6|2 but the bellows. 6| 3 remains expanded suflciently to keep the valve 6|9 in closed position until the pressure in this-bellows drops to a considerably lower-value than that at which the valve 6I! opens, for example, it may require a drop in pressure to 4 lbs. before valve 6|9 will begin to open. Likewise the initial rise in temperature will cause valve 652 to be opened but valve 61D operated by the bellows 649 will remain closed until the pressure in the line 648 and the bellows 649 drops to a value of say 4 lbs. In other words, the valves 6| 9 and 610 do not begin to open until the valves 6|8 and 652 have completely opened.

The valve 6|9 opens in response to a rise in humidity to an excessively high value such that the flapper valve 535 is nearly or entirely closed whereupon the pressure in the line 596 increases to very nearly line pressure and accordingly the pressure of bellows 592 and the lines 583 and 6|| will have dropped to a very low value. The openingof valve 6I9 will cause a decrease in pressure of the spring inthe valve 26 and the superheat required to open the valve will be decreased and the effective cooling area of coil 20 will increase. Similarly. if the temperature in the space reaches a very high value the pressure within the bellows 649 will become low enough to permit the opening of valve 616 thus relieving the pressure in the bellows 630 and lower the back pressure upon the evaporator. It will therefore' be seen that the bellows 6 I3 acts as a. limit control to increase the effective cooling area of the evaporator as the humidity within the space reaches an excessively high value.irrespective of the temperature within the space and similarly the bellows 649 acts as a limit control to reduce they back, pressure upon the compressor if the temperaturein the space reaches an excessively high value rel gardless of the humidity existing therein. The

` system so far described therefore has the same sequence of operation as that described in connection with Figure 3.

In addition, suitable control devices 680 and Bal-may be positioned in the fresh air inlet. Control 680 may include a cylindrical member 682 having a high coellicient of expansion and to which is connected a rod 683 having a low eeemeieitfsespension ena piveteuy connected l' T2,292,483/` Y! dows will 't take place. Thelowering of the' at its upper end\to"a\lever Il l pivoted at 685,

this lever controlling thewwslof air from an orifice 686.

This ermee .m ameeted by-V meens of pipes ssi, ses, and nato the resine-* a pipe 692v connected to the interior ofthe bellows 525. VAlso connected by means of a branch pipe 693 to the pipe 592 is the bellows 543. As

the. pressure within the bellows m; decreases the control point of the humidity responsive device is lowered proportionately by means of adjusting screws 532. Decrease inl pressure within bellows 525 increases the control point of the temperature responsivedevice. As the outside temperature dropsbelow a predetermined value, the expansible element 882 will contract whereupon the pivoted valve member 68,4v will move upwardly and vent the line 581 whereupon the `pressure in the bellows 525 and 543 will decrease, the control point of the humidity-responsive elelment will be lowered and the control point of the temperature responsive element will be raised. This control function is intended to take place during the heating cycle when theoutdoor temperature drops to such a value that frosting of the window panes-would result were the humidity not lowered. With a lowered relative humidity the temperature within the space relative humidity is-accompanied yby an increase in temperature in the space so that the eilectlvev temperature thereof may be kept substantially the cooling season when the outuinaava andoor temperature rises Vthe Yimioor teiilpel'atuiey is also increased at a slower rate so as to main- -heating coil I9, the amount of heat being suppliedb by this coil varying in accordance with n the temperature in the space. When the temperature reaches 70 the supply of heat to this coil willbe cut oit and if the temperature in lthe space rises to, for example, 70%?, the spring in the expansion valve will be adjusted to .de-

' crease the superheat required to open this valve should be raised in order to maintain a substan-V i tially constant eective temperature and accordingly the control point of the thermostat is raised so that the temperature maintained in the space will be higher as the relative humidity is lowered.

The controller 68| is-similar to the controller 680 except that this controller causes the opening of orifice'lll upon an increase in temperature of the fresh air supply above a predetermined value. The valve 10| is positioned below the oriilce 108, this valve being pivoted at '|02 and connected to the rod |03 which is in turn connected at the bottom to the member 104 having a. high coecient of expansion. Accordinglyl sults4 in summer air conditioning, the temperaturel of the air within `the conditioned space should increase as the outdoor temperature increases but at a somewhat slower rate in order that too much discomfort will vnot be felt by the occupants of the space in going from indoors to outdoors. However, when the temperature of the space 'is increased during the summertime, inv order that conditions will remain comfort- 'able, the relative humidity should be decreased /to some extent as the indoor temperature increases. By reason of the controller 68| raising the control point of the thermostat and lowering the control point of the humidity responso that the effective cooling area of the coil 20 will increase as the temperature rises. This spring may b e adjusted so that at 73, for example,(the valve will'be operated by the smallest amount of superheat, or in other words, at 73 the area'of the coil available for cooling will be' at almaximum. y

The humidity controller may operate to mainbeing conditioned.' A drop in humidity below this value will cause the valve controlling the humidier to open so Nthat water vapor will be supplied to the space, the amount of water vaporv being. supplied increasing as the humidity in the space decreases. When the humidity rises to .Y troller but shouldthe humidity rise/to say 51% sive element this result is successfully attained.

50%, for lexample, the humidifier may be entirely. shut down under the action of the humidity conthe temperature maintained at the evaporator 20 will begin to be lowered,L in Figure 1 b'y lowering the suction pressure maintained by the compressor and inhthe other forms of the invention by lowering the back pressure of the evaporator. The humidity controller may control the temperature of the coil so that at 55% relative humidity for example the coil will be operating at its lowest possible temperature. n

Assuming now thatthe humidity in the space is at the desired value of say 50% and the teming area of the evaporator at the maximum value,

but after the temperature exceeds 73", for examditions do increase above 73, the temperature of the evaporator will be progressively lowered.

^ tain a humidity of, for example, 50% in the space perature has risen above 73, the expansion valve s 25 will be operated to maintain the effective cool- Assume now that the temperature in the space is at the desired value of '70 but the humidity has risen above 55%. The rise in humidity from 50 to 55% willlowerthe temperature of the evaporator to its minimum value but since the temperature controller is not calling for cooling, the

eifective cooling area of. the evaporator will be at a minimum. As the humidity increases above 55% the tension of the spring within the expansion valve will be lessened and the effective cooling area of the evaporator willincreasl as the A humidity in the space -increases above 55 evaporator.

It will of course be obvious that should the temperature in the space be so low that heat is being supplied thereto by the coil I9, the operation of the evaporator for dehumidification, if the humidity -in the space is too high, will notlbe affected and conversely if the humidity in the space is below 50% so that humidity is being supplied to the air, the operation of the evaporator in lowering the temperature within the space. if the temperature therein is above 70 /2, for example, will notbe affected.

It will also be obvious that, if desired, the controls may be reversed so that the effective cooling area oi' the evaporator is primarily under the control of the humidity responsive means, and

the temperature of the evaporator is primarily scope of the appended claims.

I claim:

1. In an air conditioning system, a refrigeration apparatus including an evaporator for reducing the temperature of the air to be conditioned, a valve for controlling the ilow of refrigerant to the evaporator, means responsive to suction pressure and the temperature of the refrigerant at the evaporator outlet for controlling the position of said valve whereby the superheat at the outlet of the evaporator may be controlled andv flooding of the evaporator'prevented, means responsive to the attainmentof a high temperature in the space being conditioned for further controlling said valve to reducethe degree of superheat maintained at the evaporator outlet and to .the attainment of an excessively high humidity in the space for also controlling said valve to reduce the degree of sperheat, and

creasing the temperature of the refrigerant in the evaporator, and means responsive to excessive humidity conditions in the space for decreas- -ing the amount of super-heat at the evaporator outlet required to cause the opening of said-valve.

3. In an air conditioning'system, a refrigeration system including a compressor, a condenser and an evaporator, valve means for controlling the flow of refrigerant from the condenser to the evaporator, means responsive to the temperature of the air being conditioned for controlling the valve meanswhereby the effective cooling surface of the evaporator is varied in accordance with the temperature of the. air being conditioned, back pressure controlling means for controlling the pressure in the evaporator, humidity responsive means in control of said back pressure controlling means, and meansl responsive to the pressure differential across said back pressure controlling means for controlling the oper- Y ation of the compressor.

4. In an air conditioning system, a refrigeration system including a, compressor, a condenser, and an evaporator, valve means for controlling the ow of refrigerant from the condenser to the evaporator, back pressure controlling means including humidity responsive ineans for controlling the pressure in said evaporator whereby the temperature of the refrigerant in the evaporator varies in accordance with the,r humidity in the space being conditioned, and means responsive t the pressure differential across said back pressure controlling means for controlling the operation of the compressor.

5. In an air conditioningsystem, a refrigeration system including a compressor, a, condenser and an evaporator for controlling the condition of air, valve means fon controlling the ow of rethe operation of the compressor.

means responsive to the attainment of a high humidity in the space being conditioned for reducing the temperature of Ythe refrigerant in the evaporator and to the attainment of an exces- 'sivelyhigh temperature in the space for also reducing the temperature of the refrigerant in the 2. In an air conditioning system, means for conditioning air including a heating means, a

humidify'lng means and a cooling and dehumidifying means, said cooling and dehumidifying means comprising a refrigeration system including an evaporator, an expansion valve for controlling the flow. of refrigerant to the evaporator, means responsive to the superheatat the outlet of the'evaporator for controlling the position of said' valve, means responsive to the temperature in the space being conditioned for controlling the heating means and for controlling-the amount of superheat required to cause the opening of said valve, means responsive to the'humidity in the space being conditioned for lcontrolling the humidifylng means'and the temperature of. the refrigerant in said expansion coil, limit control means responsive to an increase in temperature from a normal range to an excessive temperature range-in the space for de- 6. In an airconditioning system, a refrigeration system including a compressor, a. condenser andan evaporate thermostaticvalve means for controlling the flow of refrigerant from the condenser to the evaporator, back pressure control means for controlling the pressure within the evaporatoryelectrically operated means in control of said thermostatic valve means to vary the superheat maintained at the evaporator outlet, electrically operated means in control of the back pressure controlling means for varying the pressure maintained within the' evaporator, temperature and humidity responsive means in control of both of said electrically operated means, and means responsive to the differential in pressure across said back pressure controlling means for controlling the operation of said compressor.

'1. In an air conditioning system, av refrigeration system including a compressor, a condenser and an evaporator, means including a back pressure controller for controlling the temperature of said evaporator, meansresponsive to the humidity of the air being conditioned for adjusting saidback pressure controller, means responsive to the attainment of an excessive temperature of the air being conditioned for further adjusting said back pressuge controller, an expansion valve 2,292,486 compressor toy the evaporator, means responsive ytroller including a valve for controlling the flow from the evaporator to the compressor, means responsive to the pressure on the suction side of Vthe evaporator for controlling the position of .said valve, spring means opposing the opening of said valve, and means responsive to the pressure drop across said back pressure controller for controlling the operation of said compressor.

9. In a refrigeration system including a compressor, a condenser and an evaporator, a back pressure controller for controlling the temperature of the evaporator, said back pressure controller including a valve for controlling the iiow from the evaporator to the compressor, means responsive to the pressure on the suction side of the evaporator for controlling the position of said valve, spring means opposing the opening of said valve, means responsive tothe pressure drop across said back pressure controller for controlling the operation of said compressor, said last named means including a circuit controlling means, and means responsive to the pressurel on the high pressure side of said valve and the pressu're on the low pressure side of said valve for controlling said circuit controlling means.

10. 'In an air conditioning system, temperature changing means for a space to be conditioned, humidity changing means for a space to be conditioned, means responsive to. the temperature of the space being conditioned in control of said temperature changing means, means responsive to the humidity of the space being conditioned in control of Asaid humidity changing means, means responsive to increases in outdoor teml perature above a predetermined value or decreases in outdoor temperaturebelow a second predetermined value for raising the control point of the temperature' responsive means and lowering the control point of the humidity responsive means.

temperature increases, a device for` controlling the pressure in said evaporator, means responsive to the humidity of the air being conditioned for adjusting said deviceso that the pressure in the evaporator decreases Vas the humidity increases, means responsive to increases in outdoor temperature for ldecreasing the eilect of said temperature responsive means on said expansion valve and simultaneously increasing the eiect of.

said humidity responsive means on said pressure controlling device.

12. An evaporatorA for controlling the condition of air, a thermostatic expansion valve for controlling the supply of refrigerant to said evaporator, said valve including a valve member and a valve seat, spring means Abiasing said valve member towards said valve seat, pressure responsive means responsive to the superheat'at the evaporator outlet for opening said valve against the force exerted by said spring means, an electric motor controlling the force exerted by said spring means, and means'responsive to the psychometric condition of the air being controlled by the evaporator in control of said electric motor, whereby the amount of superheat at the evaporator outletl and accordingly the effective cooling surface of the evaporator is varied in accordance with the psychrometric condition of the air being controlled by the evaporator.

13.l In a refrigeration system, including a compre/ssor, a condenser and anevaporator, a back pressure regulator in the line between the evaporator and the compressor for controlling the pressure within the evaporator, a .differential pressure controller for controlling the compressor in accordance with the pressure drop across said back pressure regulator, said differential pressure controller comprising a bellows consure regulatorLa second bellows connected to the low pressure side of the back pressure regulator, a lever actuated by said bellows in accordance with variations 'in' pressure din'erential between said bellows, circuit controlling means lfor said compressor operated by said lever and'moved to circuit opening position upon the attainment of a predetermined pressure differential betwen said bellows, a. spring'biasing said lever toward circuit making position, a pivoted device mounted in the path` of said lever toward circuit breaking position andbiased in a direction to oppose said movement of said, lever, and means limiting movement of said device in said direction.

14. A differential pressure controller including a pair of expansible chambers, said expansible chambers having 'communication' withfluids at different pressures and expanding in response to increasing pressure of said fluids, a lever pivoted intermediate said members and. bearing-against the movable portions thereof, spring means biasu ing said lever in the direction opposite to that in which it is moved in response to an increase in the pressure differential between said chambers, a control device operated in response to a predetermined movement of said lever, a second spring means, a second lever connectedv to said second spring and biased in the path of movement of one end of said iirst lever when said lirst lever is moving in response to an increase in f pressure differential within said expansible chambers, and means limiting the movement of said second lever in the directionlin which it is moved by said second spring means. l5. Valve controlling means for a valve having a pressure responsive deviceior causing the opening of said valve and a spring opposing the opening of 4said valve, means controlling the force exerted by'said spring and accordingly the force required to open said valve, said means comprising a stein connected to said spring, the

'position of-said stem controllingthe tension of .said spring, a lever having one end portion bearing against said stem and being pivoted at the other end to a supporting means, means biasing said lever against said stem, condition responsive means for moving said lever away from said4 stem against the force of said biasing means whereby the vstem is free to move in the same direction and relieve the force of saidspring,- said lever having a portion projecting beyond said stem,4 a second lever underlying the projecting end of said first lever, and second condition responsive means acting upon said second lever to move said rst lever away from said stem, whereby said spring is under the control of two separate actuating means.

16. In an air conditioning system, temperature changing means, humidity changing means, condition responsive means in control of said temperature and humidity changing means, means lresponsive to increases in outdoor temperature above a predetermined value or decreases in outdoor temperature below a second predetermined value for varying the control point of the condition responsive means in a manner so that the temperature maintained by the temperature changing means is increased and the humidity maintained by the humidity changing means is decreased. l

17. In an air conditioning system, a condition responsive means, a pressure operated device connected thereto to`vary the control action of said condition responsive means in accordance with the pressure in said device, means supplying pressure to said device, said pressure supplying means having a bleed line connected thereto and provided with a pair of parallelly arranged orices, valve means controlling the ilow of air from said orifices, means causing one of,said valve means to open asthe temperature at a predetermined location `drops be- A theevaporator are both responsive to the temperature and the humidity in the space being conditioned.

of said valve, means responsive to medium high 18. In an air conditioning system, condition I changing means, pressure operated means controlling the condition changing eiect of said condition changing means, means supplying pressure to said pressure operated means, a bleed pressure operated meansv for moving said valve temperature and excessively high humidity in the space being conditioned in control of said rst mentioned electric motor, and means responsive to medium high humidity and excessively high temperature'in the space beingconditioned in control of the second mentioned electric motor.

2l. In 4an air conditioning system, a refrigeration apparatus including an evaporator for reducing the temperature of the air to'be conditioned, a valve for controlling the flow of refrigerant to said evaporator, means responsive to the superheat at the outlet of the evaporator for controlling the position of said valve, and means responsive to the attainment of a high temperature in the space .being conditioned for further controlling the position of the valve to reduce the degree of superheat maintained at the evaporator outlet and to the attainment of van excessively high humidity in the space forv also controlling said v alve to'reduce the degree of superheat.

22. In an air conditioning system, a refrigeraf tionfed, means for .controlling the temperature .and eil'ective cooling surface of said evaporator,

dium high temperature and excessively high hu- .said means including means responsive to memidity in the space being conditioned for conmeans to closed positions, means biasing said valve means to open positions, one of said last 4 named pressure operated means Vbeing arranged to permit the opening of the valve means controlled thereby when the pressure therein dropsY to a predetermined value, the other of said last named pressure operated means being arranged to permit the opening of the valve means controlled thereby when the pressure therein drops to variations in temperature within an excessivelyhigh temperature range and to variations in Ahumidity within a medium high humidity range in the space being conditioned for varying the temperature'of the evaporator.

I means including an evaporator coil of a refrigto a lower predetermined value, a rst condition responsive means controlling the pressure withinl one of said last named pressure operated means, f

and a second condition responsive means oo ntrolling thepressure in the other. of said'last named pressure operated means.

19. In an air conditioning system, a refrigeration system including a compressor, a condenser and an evaporator, a valve for controlling the flow of refrigerant from the condenser tothe evaporator, an electric motor in control of said valve, a back pressure controller controlling the ilow of refrigerant from the evaporator to the compressor, an 'electric motor in control of said valve, means responsive to the humidity in the space being conditioned in control of both of said motors, and mear-.s responsive to the temperature in the space being conditioned in control of both of said motors, whereby the flow of refrigerant to the evaporator and the pressure in spnsive .to the h conditioned for controlling the humidifying.

23.1In an air conditioning system, means for conditioning air including a heating means, a

eration "system, first control means for varying the temperature of said evaporator coil and second control means for varying the enective cooling surface of said e porator coil, means redity in the space being means and said' ilrst control means for varying the temperature of said evaporator, means rcsponsive to the temperature ofthe space being conditioned for controlling the heating means and second control means for varying the enective cooling surface of the evaporator coil, means the evaporator.

i HAROLD L. STEINFELD. 

